Abstract:This study examines clustering and hardening in W-2 at.% Re and W-1 at.% Re-1 at.% Os alloys induced by 2 MeV W + ion irradiation at 573 and 773 K. Such clusters are known precursors to the formation of embrittling precipitates, a potentially life-limiting phenomenon in the operation of fusion reactor components. Increases in hardness were studied using nanoindentation. The presence of osmium significantly increased postirradiation hardening. Atom probe tomography analysis revealed clustering in both alloys, w… Show more
“…At least ten readings were obtained in the HEA matrix to avoid the effect of chemical inhomogeneity in order to represent the actual hardness of xW s , and the average value was used. Figure 6(a) summarizes the influence of the chemical composition on the hardness of xW s .Figure 6( a ) Effects of the composition on the hardness of xW s , ( b ) true stress-true strain curves of xW s , ( c ) variation in the compressive yield strength and fracture strain of xW s with varying compositions and a comparison with pure tungsten (this work), TaNbWMoV and TaNbWMo 93 and ( d ) Comparison of the hardness levels of xW s with W-V (W-3.5at.%V, W-16at.%V and W-21.3at.%V) 44 , W-Re (W-2at.%Re 48 and W-24.7at.%Re-SPS at 1500 °C) 47 , W-Cr (W-30at.%Cr, W-50at.%Cr and W-70at.%Cr) 58 , W-Mo (W-32.2at.%Mo, W-45.5at.%Mo and W-56.3at.%Mo) 56 , W-Ta (W-99at.%Ta, W-96at.%Ta and W-90.7at.%Ta) 50 , and W-Ti (W-29at.%Ti, W-40.2at.%Ti and W-48.8at.%Ti) 54 .
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The WxTaTiVCr high-entropy alloy with 32at.% of tungsten (W) and its derivative alloys with 42 to 90at.% of W with in-situ TiC were prepared via the mixing of elemental W, Ta, Ti, V and Cr powders followed by spark plasma sintering for the development of reduced-activation alloys for fusion plasma-facing materials. Characterization of the sintered samples revealed a BCC lattice and a multi-phase structure. The selected-area diffraction patterns confirmed the formation of TiC in the high-entropy alloy and its derivative alloys. It revealed the development of C15 (cubic) Laves phases as well in alloys with 71 to 90at.% W. A mechanical examination of the samples revealed a more than twofold improvement in the hardness and strength due to solid-solution strengthening and dispersion strengthening. This study explored the potential of powder metallurgy processing for the fabrication of a high-entropy alloy and other derived compositions with enhanced hardness and strength.
“…At least ten readings were obtained in the HEA matrix to avoid the effect of chemical inhomogeneity in order to represent the actual hardness of xW s , and the average value was used. Figure 6(a) summarizes the influence of the chemical composition on the hardness of xW s .Figure 6( a ) Effects of the composition on the hardness of xW s , ( b ) true stress-true strain curves of xW s , ( c ) variation in the compressive yield strength and fracture strain of xW s with varying compositions and a comparison with pure tungsten (this work), TaNbWMoV and TaNbWMo 93 and ( d ) Comparison of the hardness levels of xW s with W-V (W-3.5at.%V, W-16at.%V and W-21.3at.%V) 44 , W-Re (W-2at.%Re 48 and W-24.7at.%Re-SPS at 1500 °C) 47 , W-Cr (W-30at.%Cr, W-50at.%Cr and W-70at.%Cr) 58 , W-Mo (W-32.2at.%Mo, W-45.5at.%Mo and W-56.3at.%Mo) 56 , W-Ta (W-99at.%Ta, W-96at.%Ta and W-90.7at.%Ta) 50 , and W-Ti (W-29at.%Ti, W-40.2at.%Ti and W-48.8at.%Ti) 54 .
…”
The WxTaTiVCr high-entropy alloy with 32at.% of tungsten (W) and its derivative alloys with 42 to 90at.% of W with in-situ TiC were prepared via the mixing of elemental W, Ta, Ti, V and Cr powders followed by spark plasma sintering for the development of reduced-activation alloys for fusion plasma-facing materials. Characterization of the sintered samples revealed a BCC lattice and a multi-phase structure. The selected-area diffraction patterns confirmed the formation of TiC in the high-entropy alloy and its derivative alloys. It revealed the development of C15 (cubic) Laves phases as well in alloys with 71 to 90at.% W. A mechanical examination of the samples revealed a more than twofold improvement in the hardness and strength due to solid-solution strengthening and dispersion strengthening. This study explored the potential of powder metallurgy processing for the fabrication of a high-entropy alloy and other derived compositions with enhanced hardness and strength.
“…grain boundaries and dislocations) and the rest. Atom probe tomography analysis of W-Re alloy after ion irradiation by Xu et al 7. shows the majority of aggregated Re atoms are in the bulk region.…”
Section: Discussionmentioning
confidence: 99%
“…One can think of a few possible mechanisms for RIP. For example, extended defects such as dislocations or grain boundaries might provide nucleation sites for aggregation, but an experiment7 shows that the aggregation occurs without extended defects. Another hypothesis is that vacancy or interstitial clustering might cause the aggregation, but the RIP is not correlated to the growth of voids and dislocation loops8.…”
Modeling the evolution of radiation-induced defects is important for finding radiation-resistant materials, which would be greatly appreciated in nuclear applications. We apply the density functional theory combined with comprehensive analyses of massive experimental database to indicate a mechanism to mitigate the effect of radiation on W crystals by adding particular solute elements that change the migration property of interstitials. The resultant mechanism is applicable to any body-centered-cubic (BCC) metals whose self-interstitial atoms become a stable crowdion and is expected to provide a general guideline for computational design of radiation-resistant alloys in the field of nuclear applications.
“…2MeV W + ion irradiation induced the formation the Re-rich clusters in the binary W-2 at. % Re alloy and which will cause likely irradiation hardening [11]. The mechanism of radiation-induced has been explored by firstprinciples method [12].…”
Transmutation elements are the essential products in plasma facing materials tungsten, and have further effects on point defects evolution resulted by radiation. Here, transmutation elements Re and Ta atoms have been selected to assess the effects on property of vacancy and vacancy cluster in W material via first-principles calculations. The formation energy indicates mono-vacancy is more likely to form in W-Re system than pure W and W-Ta system. Both Re and Ta have reduced the diffusion barrier energy in the mono-vacancy migration. The calculation presents that vacancy cluster prefers to grow up by combining another vacancy cluster relative to a single mono-vacancy. Re is favorable to the nucleation and growth of vacancies clusters, while Ta has a suppressive effect on the aggregation of small vacancy cluster. The emphasis analysis is obtained according the volumetric dependent strain. Vacancy dissociation calculations show that the dissociation of vacancy clusters is easier to begin with a single vacancy dissociation process.
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